I moved Bubbles into him new 2foot luxury apartment on monday. I have 3 potted water plants in it and some floating weed on the top, a coral tunnel and a pottery cup as a cave, but it's still a little barren looking.

He's been tearing around it like a mad thing since he was moved in! Mostly he does laps of the back of the tank and hardly comes to the front.. it can be quite hard to get his attention now, though when he realises you're waving at him he comes to the front to see if you have food.
He has managed to build himself a little bubble nest, so he mustn't be doing laps all day. He just doesn't seem his usual, placid self. He's even a bit jumpy about objects being moved around outside his tank.
Does anyone have any suggestions or advice? I'm wondering if he may be feeling too exposed... or is this normal betta behaviour?
He was very curious and always following us around in his previous (small) accomodation...

I'm willing to be he is feeling a bit exposed. If you don't want to add more live plants you should try adding some silk ones. Maybe a cave or two. Give him more cover and a few days; he'll be back to normal again soon.

I think he has spent most of his life in round objects, we had him in a bowl for a week and the guy we bought him off (out of a jar) said he keeps all his fighters in jars...
Bubbles has spent a lot of time butting the walls of his 2f tank so far.
I have covered 3 sides and the top.. i hope he adjusts soon... he's stressing me out! lol

Sounds like he is just adjusting to the new, larger tank.. if he were stressed more likely he wouldn't be active, and instead hiding constantly. But active bettas are a sign of healthy and generally happy bettas.
Breeders use jars to separate young males before they are sold, and even ones they are breeding. Yours actually sounds as if he took to the larger tank quite well.
Covering up the walls won't stop him from pacing.. but the new plants may as they will give him more mental stimulation and places to swim through. But I wouldn't say for sure. If he is flaring at the walls, then he is seeing his reflection, and that is taken care of by making sure the room light is always on when the tank light is on (or there is enough natural light coming in during the day).
He'll eventually calm down and he didn't forget about you.. I had the same thing when I upgraded one of my boys from a round tank to a larger rectangle. Just enjoy him and be happy he is healthy and is active.

The weather has been a little cold so we bought a heater for bubbles and over the last couple days we've raised his tank temp from 22c to 26c. He's calmed down heaps and started paying attention to us again (it could have been to do with the lecture I gave him on how he was being a very callous and ungrateful pet fish). He's still chasing the sides of the tank a bit, but not constantly, it must be that he's seeing his reflection.

I also got him a cave, which he doesn't even look at, and a snail friend, which he headbutts occasionally when he bothers to notice it.

I'm so glad he's calmed down, I was getting terribly worried!

Thanks for the suggestions everyone!

p.s. isn't it funny how we got him in a jar and he was cool as and calm in there. After a week in a tank he has a massive tantrum about having to spend 1/2 and hour in a jar while we relocated his tank... spoilt lil fishy!